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تسجيل مستخدم جديدJPCam: A 1.2Gpixel camera for the J-PAS survey
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JPCam is a 14-CCD mosaic camera, using the new e2v 9k-by-9k 10microm-pixel 16-channel detectors, to be deployed on a dedicated 2.55m wide-field telescope at the OAJ (Observatorio Astrofisico de Javalambre) in Aragon, Spain. The camera is designed to perform a Baryon Acoustic Oscillations (BAO) survey of the northern sky. The J-PAS survey strategy will use 54 relatively narrow-band (~13.8nm) filters equi-spaced between 370 and 920nm plus 3 broad-band filters to achieve unprecedented photometric red-shift accuracies for faint galaxies over ~8000 square degrees of sky. The cryostat, detector mosaic and read electronics is being supplied by e2v under contract to J-PAS while the mechanical structure, housing the shutter and filter assembly, is being designed and constructed by a Brazilian consortium led by INPE (Instituto Nacional de Pesquisas Espaciais). Four sets of 14 filters are placed in the ambient environment, just above the dewar window but directly in line with the detectors, leading to a mosaic having ~10mm gaps between each CCD. The massive 500mm aperture shutter is expected to be supplied by the Argelander-Institut fur Astronomie, Bonn. We will present an overview of JPCam, from the filter configuration through to the CCD mosaic camera. A brief outline of the main J-PAS science projects will be included.
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The Javalambre-Physics of the Accelerated Universe Astrophysical Survey (J-PAS) is a narrow band, very wide field Cosmological Survey to be carried out from the Javalambre Observatory in Spain with a purpose-built, dedicated 2.5m telescope and a 4.7
sq.deg. camera with 1.2Gpix. Starting in late 2015, J-PAS will observe 8500sq.deg. of Northern Sky and measure $0.003(1+z)$ photo-z for $9times10^7$ LRG and ELG galaxies plus several million QSOs, sampling an effective volume of $sim 14$ Gpc$^3$ up to $z=1.3$ and becoming the first radial BAO experiment to reach Stage IV. J-PAS will detect $7times 10^5$ galaxy clusters and groups, setting constrains on Dark Energy which rival those obtained from its BAO measurements. Thanks to the superb characteristics of the site (seeing ~0.7 arcsec), J-PAS is expected to obtain a deep, sub-arcsec image of the Northern sky, which combined with its unique photo-z precision will produce one of the most powerful cosmological lensing surveys before the arrival of Euclid. J-PAS unprecedented spectral time domain information will enable a self-contained SN survey that, without the need for external spectroscopic follow-up, will detect, classify and measure $sigma_zsim 0.5%$ redshifts for $sim 4000$ SNeIa and $sim 900$ core-collapse SNe. The key to the J-PAS potential is its innovative approach: a contiguous system of 54 filters with $145AA$ width, placed $100AA$ apart over a multi-degree FoV is a powerful redshift machine, with the survey speed of a 4000 multiplexing low resolution spectrograph, but many times cheaper and much faster to build. The J-PAS camera is equivalent to a 4.7 sq.deg. IFU and it will produce a time-resolved, 3D image of the Northern Sky with a very wide range of Astrophysical applications in Galaxy Evolution, the nearby Universe and the study of resolved stellar populations.
The impending Javalambre Physics of the accelerating universe Astrophysical Survey (J-PAS) will be the first wide-field survey of $gtrsim$ 8500 deg$^2$ to reach the `stage IV category. Because of the redshift resolution afforded by 54 narrow-band fil
ters, J-PAS is particularly suitable for cluster detection in the range z$<$1. The photometric redshift dispersion is estimated to be only $sim 0.003$ with few outliers $lesssim$ 4% for galaxies brighter than $isim23$ AB, because of the sensitivity of narrow band imaging to absorption and emission lines. Here we evaluate the cluster selection function for J-PAS using N-body+semi-analytical realistic mock catalogues. We optimally detect clusters from this simulation with the Bayesian Cluster Finder, and we assess the completeness and purity of cluster detection against the mock data. The minimum halo mass threshold we find for detections of galaxy clusters and groups with both $>$80% completeness and purity is $M_h sim 5 times 10^{13}M_{odot}$ up to $zsim 0.7$. We also model the optical observable, $M^*_{rm CL}$-halo mass relation, finding a non-evolution with redshift and main scatter of $sigma_{M^*_{rm CL} | M_{rm h}}sim 0.14 ,dex$ down to a factor two lower in mass than other planned broad-band stage IV surveys, at least. For the $M_{rm h} sim 1 times 10^{14}M_{odot}$ Planck mass limit, J-PAS will arrive up to $zsim 0.85$ with a $sigma_{M^*_{rm CL} | M_{rm h}}sim 0.12 , dex$. Therefore J-PAS will provide the largest sample of clusters and groups up to $zsim 0.8$ with a mass calibration accuracy comparable to X-ray data.
We present the DSA-2000: a world-leading radio survey telescope and multi-messenger discovery engine for the next decade. The array will be the first true radio camera, outputting science-ready image data over the 0.7 - 2 GHz frequency range with a s
patial resolution of 3.5 arcsec. With 2000 x 5 m dishes, the DSA-2000 will have an equivalent point-source sensitivity to SKA1-mid, but with ten times the survey speed. The DSA-2000 is envisaged as an all-sky survey instrument complementary to the ngVLA, and as a counterpart to the LSST (optical), SPHEREx (near-infrared) and SRG/eROSITA (X-ray) all-sky surveys. Over a five-year prime phase, the DSA-2000 will image the entire sky above declination -30 degrees every four months, detecting > 1 unique billion radio sources in a combined full-Stokes sky map with 500 nJy/beam rms noise. This all-sky survey will be complemented by intermediate and deep surveys, as well as spectral and polarization image cubes. The array will be a cornerstone for multi-messenger science, serving as the principal instrument for the US pulsar timing array community, and by searching for radio afterglows of compact object mergers detected by LIGO and Virgo. The array will simultaneously detect and localize ~10,000 fast radio bursts each year, realizing their ultimate use as a cosmological tool. The DSA-2000 will be proposed to the NSF Mid-Scale Research Infrastructure-2 program with a view to first light in 2026
J-PAS will soon start imaging 8000 deg2 of the northern sky with its unique set of 56 filters (R $sim$ 60). Before, we observed 1 deg2 on the AEGIS field with an interim camera with all the J-PAS filters. With this data (miniJPAS), we aim at proving
the scientific potential of J-PAS to identify and characterize the galaxy populations with the goal of performing galaxy evolution studies across cosmic time. Several SED-fitting codes are used to constrain the stellar population properties of a complete flux-limited sample (rSDSS <= 22.5 AB) of miniJPAS galaxies that extends up to z = 1. We find consistent results on the galaxy properties derived from the different codes, independently of the galaxy spectral-type or redshift. For galaxies with SNR>=10, we estimate that the J-PAS photometric system allows to derive stellar population properties with a precision that is equivalent to that obtained with spectroscopic surveys of similar SNR. By using the dust-corrected (u-r) colour-mass diagram, a powerful proxy to characterize galaxy populations, we find that the fraction of red and blue galaxies evolves with cosmic time, with red galaxies being $sim$ 38% and $sim$ 18% of the whole population at z = 0.1 and z = 0.5, respectively. At all redshifts, the more massive galaxies belong to the red sequence and these galaxies are typically older and more metal rich than their counterparts in the blue cloud. Our results confirm that with J-PAS data we will be able to analyze large samples of galaxies up to z $sim$ 1, with galaxy stellar masses above of log(M$_*$/M$_{odot}$) $sim$ 8.9, 9.5, and 9.9 at z = 0.3, 0.5, and 0.7, respectively. The SFH of a complete sub-sample of galaxies selected at z $sim$ 0.1 with log(M$_*$/M$_{odot}$) > 8.3 constrain the cosmic evolution of the star formation rate density up to z $sim$ 3 in good agreement with results from cosmological surveys.
We consider a cosmological model where dark matter and dark energy feature a coupling that only affects their momentum transfer in the corresponding Euler equations. We perform a fit to cosmological observables and confirm previous findings within th
ese scenarios that favour the presence of a coupling at more than $3sigma$. This improvement is driven by the Sunyaev-Zeldovich data. We subsequently perform a forecast for future J-PAS data and find that clustering measurements will permit to clearly discern the presence of an interaction within a few percent level with the uncoupled case at more than $10sigma$ when the complete survey, covering $8500$ sq. deg., is considered. We found that the inclusion of weak lensing measurements will not help to further constrain the coupling parameter. For completeness, we compare to forecasts for DESI and Euclid, which provide similar discriminating power.
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